Thoughts on Cannabis and Schizophrenia

Cannabis does not cause schizophrenia

Yesterday I read a story in the Daily Mirror whose headlined blared, “Scientists discover a genetic link between cannabis use and SCHIZOPHRENIA”. Though it is meant to tell you that the journalists think that cannabis causes schizophrenia, the fact of the matter is that the study in question does not go so far. Let's firstly look at the research and then do a little commentary.

Genetic link?

The research in question was published in Nature Neuroscience by academics at the Radboud University in Nijmegen in the Netherlands. Looking at the genetic make up of 180,000 people, the scale is sufficiently large that any strong statistics garnered from it would have strength in numbers. Small-scale studies have a weakness in that it could be a narrow group of people with similar characteristics - you can't put that argument against something about 180,000 people. So far so good!

The university press release stated, “The study identified 35 different genes associated with cannabis use with the strongest associations in the gene CADM2. “CADM2 has already been associated with risky behaviour, personality and alcohol use,” said Jacqueline Vink of Radboud University, and the study’s lead author.”

The press release continued, “The study found a genetic overlap between cannabis use and the use of tobacco and alcohol. There was a similar overlap between cannabis use and personality types that were prone to more risky behaviour or were more extraverted.”

Regarding cannabis use, the research also found links between those who use cannabis and those who have schizophrenia. This proves no causal link just commonality. If a large number of cows with black spots were hit by trains (and fewer with brown spots) this does not mean to say that cows with black spots are prone to jumping in front of trains - just that those type of cows get hit!

The next statement is where it gets interesting: “The researchers used an analysis technique called "Mendelian randomisation" to show a causal relationship between schizophrenia and an increased risk of cannabis use.” This is where things get open to interpretation.

The statement continued, “This may indicate that people with schizophrenia use cannabis as a form of self-medication.” Where things go a little off-track is the next statement which was not shown in the research - we emphasise this in bold: “However, the researchers cannot exclude a reverse cause-and-effect relationship, meaning that cannabis use could contribute to the risk of schizophrenia.” This statement in bold is purely commentary on the part of the scientists and has no scientific basis except the smoke around a potential fire.

A little about me

When diagnosed with paranoid schizophrenia in 1999, I was given the narrative by my psychiatric team that my cannabis use caused schizophrenia. What made me move into cannabis writing was a number of discussions with leading schizophrenia researchers who said that despite what you read in the media, there is no strong causal link between cannabis use and schizophrenia. To me that this was an epiphany, and opened my eyes to the fact that schizophrenia in almost every case is caused by multiple different factors. If it was so simple that 20 joints a week could send you over the edge they would have found the link by now. I have now been covering this story off and on for around 14 years. Once again I see another indicator of a link between cannabis and schizophrenia but nothing I could remotely call certain.

Research has repeatedly shown that cannabis could be an ingredient of schizophrenia in much the same way as being stressed out in childhood is, as well as genetic factors. There are genetic factors in my family. I had a ridiculously stressful adolescence. I also consumed too much alcohol (known to cause psychosis), took a lot of LSD and magic mushrooms, and was permanently stoned for the first two years of my first degree at university. No one has nailed cannabis as an ingredient down for certain though – and nor does this study.

Cannabis and psychosis

One thing is rock-solid certain - there is a temporary form of psychosis called cannabis psychosis. Many years ago the then chair of the Advisory Council on the Misuse of Drugs (ACMD) explained to me for a feature I was writing for Mental Health Today that most chemicals can cause psychosis. He went as far as saying that only opioids do not cause psychosis - even too much water can cause psychosis! Tony Blair's former press secretary Alastair Campbell famously had a bout of alcohol psychosis that he recounts in his memoirs. This is why he does not drink.

Groups of people who should not touch weed

While I am very pro-cannabis I cannot go as far as saying that everybody should be allowed to use weed. I have an organic psychotic condition - I cannot smoke it myself. Those who suffer disabling paranoia from consuming the stuff would also do well to avoid it themselves. In my day psychiatric services in the UK were about recovery. Now they have been cut to the bone I would not recommend a spell in a psychiatric unit anywhere. Nor would I recommend you risk encountering mental health services if at all possible.

If you suffer paranoia between spells of consuming cannabis, cut it out altogether. If you have messed up perceptions – perhaps hearing music when not radio / stereo is on or even hearing voices / seeing or feeling things – then you should cut it out for a good three months (the time it takes to clear from your system). If your friends are smoking weed problematically, then perhaps you need to find new ones through healthy activities. Ask for psychiatric help and accept medication through your GP. Don’t end up in a situation where you are carted off by the police for being of danger to yourself or others.

Next week an inquest begins into the death of someone who was close to me. He was a heavy cannabis user and had schizophrenia. He would bleed to death from a self-inflicted wound while the police tasered the last breath out of him. Mental health services were so overstretched they made mistakes that lead to his committing suicide. While in 1999 there was a good chance of surviving cannabis psychosis or even schizophrenia as I did, I would not be so comfortable in saying that life is so good today.

Terry did self-medicate his schizophrenia with cannabis as the research above indicated, but the problem was that the cannabis exacerbated his paranoia and may have contributed to the depression that would eventually send him over the edge. Either way he did not listen to his doctors when he was originally diagnosed at around the same time as I was when resources were rich in mental health.

The basic message of this article is that you need to take care of yourself.

Cannabis does not cause schizophrenia but it does exacerbate the symptoms if you have it. People suffering paranoia after smoking or consuming weed should take a break - that's only healthy. If after that break, you consume again and you get paranoid, then perhaps weed is not the right past time for you. I love sailing in all conditions - some people get seasick as soon as they leave that dock. Sailing suits me but it doesn't suit them. Not everybody enjoys the same thing - that is the richness of life!

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